Tenses Questions
The past perfect continuous tense is used to describe an ongoing action that started in the past and continued up until another point in the past. It is formed by using "had been" + present participle (-ing form of the verb). For example, "She had been studying for hours before she took a break."
On the other hand, the past perfect tense is used to describe an action that happened before another action in the past. It is formed by using "had" + past participle of the verb. For example, "He had already finished his homework when his friends arrived."
In summary, the main difference between the past perfect continuous and past perfect tenses is that the past perfect continuous emphasizes the duration of an ongoing action in the past, while the past perfect simply states that an action happened before another action in the past.